Estudio microbiológico del proceso madurativo del queso de Mahón : elaboración de un "Starter" para su fabricación a partir de la leche pasterizada

Tesis Univ. Complutense de Madrid.Depto. de Genética, Fisiología y MicrobiologíaFac. de Ciencias BiológicasTRUEProQuestpu

Wine Spoilage Yeasts: Control Strategy

Traditionally in winemaking, sulphur dioxide (SO2) is chemically the most widely used for microflora control as antimicrobial preservative. Other tested compounds for selective yeast control are sorbic and benzoic acids. Herein, we discuss the effectiveness and the application of traditional and novel treatments and biotechnologies for chemical and biological control of wine spoilage yeasts. The versatility of the killer toxins and the antimicrobial properties of natural compounds such as carvacrol, essential oils and bioactive peptides will be considered. Some of the wine spoilage yeasts that are intended to control belong to the genera Zygosaccharomyces, Saccharomycodes and Dekkera/Brettanomyces, but also the non-Saccharomyces yeasts species dominating the first phase of fermentation (Hanseniaspora uvarum, Hansenula anomala, Metschnikowia pulcherrima, Wickerhamomyces anomalus) and some others, such as Schizosaccharomyces pombe, depending on the kind of wine to be produced

Quality and Composition of Red Wine Fermented with Schizosaccharomyces pombe as Sole Fermentative Yeast, and in Mixed and Sequential Fermentations with Saccharomyces cerevisiae

U radu je ispitana fiziologija kvasca Schizosaccharomyces pombe (soj 938) upotrijebljenog za proizvodnju crnog vina. Provedeno je više tipova fermentacija: s kvascem Schizosaccharomyces pombe 938, s mješovitom kulturom kvasaca Sc. pombe i Saccharomyces cerevisiae 796, te fermentacija prvo s pomoću Sc. pombe, a zatim s pomoću S. cerevisiae. Za dodatnu su usporedbu provedene fermentacije samo s kvascem S. cerevisiae, za što je upotrijebljen komercijalni pripravak bakterija mliječne kiseline, koje su provele malolaktičnu fermentaciju po završetku alkoholne fermentacije. Za razliku od kvasca S. cerevisiae, kvasac Sc. pombe provodi maloalkoholnu fermentaciju, pri čemu se smanjuje koncentracija jabučne kiseline u vinu. Tijekom fermentacije praćeni su sljedeći parametri: relativna gustoća; koncentracija octene, jabučne i piruvatne kiseline; početne koncentracije amino dušika i uree; te pH-vrijednost mošteva. U svim fermentacijama u kojima je sudjelovao kvasac Sc. pombe 938 jabučna je kiselina (početne koncentracije od 5,5 g/L) gotovo potpuno upotrijebljena za rast kvasaca, a nastala je umjerena koncentracija octene kiseline (manja od 0,4 g/L). Udjel je uree u tim vinima bio deset puta manji nego u vinima fermentiranim samo s kvascem S. cerevisiae 796. Senzorska su se svojstva vina dobivenih različitim tipovima fermentacija bitno razlikovala. Vina fermentirana s pomoću kvasca Sc. pombe 938 imala su najbolju kakvoću i intenzitet arome, pa su dobila najbolje ocjene pri senzorskoj analizi uzoraka vina.This work examines the physiology of Schizosaccharomyces pombe (represented by strain 938) in the production of red wine, as the sole fermentative yeast, and in mixed and sequential fermentations with Saccharomyces cerevisiae 796. For further comparison, fermentations in which Saccharomyces cerevisiae was the sole fermentative yeast were also performed; in these fermentations a commercial lactic acid bacterium was used to perform malolactic fermentation once alcoholic fermentation was complete (unlike S. cerevisiae, the Sc. pombe performs maloalcoholic fermentation and therefore removes malic acid without such help). Relative density, acetic, malic and pyruvic acid concentrations, primary amino nitrogen and urea concentrations, and pH of the musts were measured over the entire fermentation period. In all fermentations in which Sc. pombe 938 was involved, nearly all the malic acid was consumed from an initial concentration of 5.5 g/L, and moderate acetic acid concentrations below 0.4 g/L were formed. The urea content of these wines was notably lower, showing a tenfold reduction when compared with those that were made with S. cerevisiae 796 alone. The sensorial properties of the different final wines varied widely. The wines fermented with Sc. pombe 938 had maximum aroma intensity and quality, and they were preferred by the tasters

Use of Ultra-High Pressure Homogenization processing in winemaking:Control of microbial populations in grape musts and effects in sensory quality

Ultra-High Pressure Homogenization (UHPH) is a fast and efficient technique that can sterilizefluid foods at lowtemperatures or even under cooling conditions. A white must (Vitis viniferaL.) was processed at 300 MPa (inlettemperature 20 °C, in-valve temperature 98 °C, outlet temperature 25 °C, and time in valve 0.02 s) and theirperformance was compared with two untreated controls, a must that underwent a spontaneous fermentation(without SO2addition) and another must that was sulfited with 35 mg/L of total SO2and inoculated with thesameSaccharomyces cerevisiaeyeast as the UHPH-treated must. UHPH treatment led to the total elimination ofgrape microorganisms considering an initial population of 1 × 106CFU/mL in average of wild yeasts and fungiin must, and approximately 7 × 103CFU/mL of background bacteria. In a parallel assay, UHPH-processed mustwithout yeast inoculation showed absence of fermentation for eight days at 18 °C. The musts treated with UHPHshowed a lighter appearance (10%) before fermentation compared to the control. The triangular test verified theexistence of sensory differences between the wines obtained and the preference tests showed that the judgesfound the wine obtained from the UHPH-treated must more fruity (3.5/5 compared with 1.5–2 in controls) andwith better aroma.Industrial relevance:UHPH is an interesting way to process the must before fermentation allowing the reductionof sulfite addition while controlling wild and spoilage microorganisms.info:eu-repo/semantics/acceptedVersio

Optical and AFM microscopy of grape juices treated with UHPH: Effects of microstructure and nanostructure

UHPH treatment of Vitis vinifera must for winemaking leads to fragmentation of colloidal particles into smaller structures. The shear and fracture forces experienced by grape juice during valve pressurization are sufficient to reduce the particle size of grape juice to below 500 nm. As a result, the applied force can disrupt bacterial and yeast cell structures, altering or breaking down proteins, polysaccharides and enzymes. This effect is not observed for low molecular weight compounds such as monomeric pigments and phenolic structures, varietal aroma precursors, fermentable sugars, etc. Treated and untreated samples can be compared using optical and atomic force microscopy. Optical microscopy images show reduction or elimination of bacteria and yeast and changes in microstructure. On the other hand, in addition to describing topography in the nanometer range, AFM can also measure particles in comparison to other techniques such as laser diffraction (LD). This work contributes to the characterization and better understanding of the effects of UHPH on grape juice for winemaking

Use of red grape juice (concentrated and treated by UHPH) as a base to produce isotonic drinks

The physical-chemical composition, sensory characteristics, and nutritional value of the grape juice can provide sports drink (isotonic beverage) with antioxidant compounds that complement the beneficial effect of these drinks to the rehydration and replacement of minerals and carbohydrates, during physical activity. Grape juice contains mainly water, sugars, organic acids, and phenolic compounds. By diluting the sugar content of the must to 40-50 g/L, it will allow us to obtain a drink with beneficial properties for health, avoiding the addition of sweeteners. Phenolic compounds play an important role in the prevention of various diseases through their biological activities related to antioxidant, anti-inflammatory, anticancer, anti-aging, antimicrobial and cardioprotective properties. Several studies have shown that grape juice allows to improve the performance of the activity, protect against oxidative damage, and reduce inflammation during, sports activities. The polyphenolic substances present in grape musts provide sensory characteristics of interest, mainly color and aroma, important indicators for consumers when choosing this type of beverage. The anthocyanin content of musts from red varieties, gives the drink a more natural and attractive character for the consumer without the use of synthetic dyes. It is important to recognize the demand of consumers for new innovative, and healthy products, so we focus on the development of a natural, functional drink using red grape musts as a base (concentrated or treated with UHPH) as a source of polyphenols and sugars, showing interesting organoleptic properties without chemical additives, and that allows to replenish electrolytes and energy

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

SARS-CoV-2 viral load in nasopharyngeal swabs is not an independent predictor of unfavorable outcome

The aim was to assess the ability of nasopharyngeal SARS-CoV-2 viral load at first patient’s hospital evaluation to predict unfavorable outcomes. We conducted a prospective cohort study including 321 adult patients with confirmed COVID-19 through RT-PCR in nasopharyngeal swabs. Quantitative Synthetic SARS-CoV-2 RNA cycle threshold values were used to calculate the viral load in log10 copies/mL. Disease severity at the end of follow up was categorized into mild, moderate, and severe. Primary endpoint was a composite of intensive care unit (ICU) admission and/or death (n = 85, 26.4%). Univariable and multivariable logistic regression analyses were performed. Nasopharyngeal SARS-CoV-2 viral load over the second quartile (≥ 7.35 log10 copies/mL, p = 0.003) and second tertile (≥ 8.27 log10 copies/mL, p = 0.01) were associated to unfavorable outcome in the unadjusted logistic regression analysis. However, in the final multivariable analysis, viral load was not independently associated with an unfavorable outcome. Five predictors were independently associated with increased odds of ICU admission and/or death: age ≥ 70 years, SpO2, neutrophils > 7.5 × 103/µL, lactate dehydrogenase ≥ 300 U/L, and C-reactive protein ≥ 100 mg/L. In summary, nasopharyngeal SARS-CoV-2 viral load on admission is generally high in patients with COVID-19, regardless of illness severity, but it cannot be used as an independent predictor of unfavorable clinical outcome

Incidence of nitrogenous compounds of must on ethyl carbamate formation induced by lactic acid bacteria

Aims: Ethyl carbamate (EC) is a toxic compound of major concern for the hygiene quality of wines. Its natural synthesis in wine is connected to the ethanolysis of molecules such as urea (alcoholic fermentation metabolite) and citrulline and carbamyl phosphate (malolactic fermentation metabolites) during ageing. This study reports the effect of adenine, arginine, urea and ammonium phosphate of Vitis vinifera L. cv. Tempranillo must, on EC synthesis in fermented wine using two lactic acid bacteria strains under different microbiological and physicochemical conditions. Methods and results: EC was quantified by gas chromatography-mass spectrometry detection. The Lactobacillus hilgardii strain evaluated was associated with particularly high EC production. No significant effect on EC formation was observed for nitrogen enrichment of the starting must. Conclusion: Residual arginine levels at the end of alcoholic fermentation from arginine- and ammonium-enriched musts showed no direct relationship to EC levels found after incubation with either of the LAB strains. Overall results suggest that the different nitrogenous substrates added to V. vinifera L. cv. Tempranillo must do not have any influence on EC formation due to LAB growth in wines under the experimental conditions used. Significance and impact of study: The composition of the nitrogen status of must has frequently been said to be a factor of concern on the final urethane concentration of wines. High contents of arginine coming from over fertilised vineyards are known to render significant levels of urea after alcoholic fermentation if conducted by arginase (+) yeast strains. This urea is always likely to undergo ethanolysis. No significant correlations were found between any of the nitrogenous compounds tested and final EC. High levels of arginine in the starting must did not lead to greater EC concentrations in the resulting wines